Thesis (Ph.D.)--Indiana University, 2005. / (UnM)AAI3183912. Source: Dissertation Abstracts International, Volume: 66-07, Section: B, page: 3599. Chair: Lisa Pratt.

Thesis (M.S.)--University of Wisconsin--Madison, 1984. / Three folded illustrative matter in pocket. Typescript. Includes tables. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 65-67).

Thesis (M.S.)--Oregon State University, 1994. / Includes mounted photographs. One folded plate in pocket. Typescript (photocopy). Includes bibliographical references (leaves 181-185). Also available on the World Wide Web.

Thesis (Ph.D.)--Indiana University, Dept. of Geological Sciences, 2009. / Title from home page (viewed on Jul 12, 2010). Source: Dissertation Abstracts International, Volume: 70-10, Section: B, page: 6064. Adviser: Lisa M. Pratt.

Thesis (Ph.D.)--University of Melbourne, School of Earth Sciences, 2010. / Typescript. Includes bibliographical references (p. 319-350)

Thesis (B.Sc.Hons.) - University of Queensland, 2004. / Two accompanying maps in back pocket. Includes bibliographical references.

Thesis (Ph.D.)--Indiana University, Dept. of Geological Sciences, 2005. / Source: Dissertation Abstracts International, Volume: 66-07, Section: B, page: 3599. Chair: Lisa Pratt. Title from dissertation home page (viewed Oct. 5, 2006).

<p>Changes in the concentration of atmospheric carbon dioxide (pCO2) affect global climate. Accurate determination of paleo-pCO2 can therefore provide information on the response of climate to changing pCO2. Such pCO2 proxies have been developed from a variety of terrestrial (e.g., plant stomata, paleosol carbonate, and liverworts) and marine (e.g., alkenones and boron) substrates. However, these proxies show a wide range of values and uncertainty throughout the Cenozoic and especially for the early Paleogene (53-63 mya). Here, I demonstrate the use of the carbon isotope composition of n-alkanes extracted from C3 plant waxes as an accurate recorder of changes in atmospheric chemistry. My results show that the uncertainty and range of pCO2 estimates determined using this new proxy are similar to other proxies. Because n-alkanes are abundant, chemically resistant, and not subject to degradation, this proxy represents an excellent opportunity to reconstruct pCO2 across the last 400 Myr of Earth history. By examining across 4 different chain lengths (n-27, n-29, n- 31, and n-33), I find that only n-29 and n-31 show clear changes in carbon isotope discrimination in response to changes pCO2, whereas chain-lengths n-27 and n-31 did not show any significant response. Using chain lengths n-29 and n-31, I calculate early Paleogene pCO2 = 566 ? 190 and 469 ? 165 ppmv (median ? 1?), respectively. These results demonstrate that n-alkanes can serve as a potential pCO2 proxy across geologic timescales.

Analyses of sediment cores from two small lakes in the southwest Yukon, Jellybean Lake (60.35°N, 134.80°W, 730-m a.s.l.) and Marcella Lake (60.074°N, 133.808°W, 697-m a.s.l.) provide records of Holocene changes in atmospheric circulation, hydrology and humidity from millennial time-scales up to 5–20-year resolution. An Aleutian Low mechanism for Holocene climate variability in the North Pacific sub-Arctic region is developed from the results of oxygen isotope records from these new sites. The climatic reconstruction and proposed mechanism lays the framework for evaluation of the paleoenvironrnental and human response to climate changes in the region. Jellybean Lake water reflects the isotope composition of mean annual precipitation and Holocene variations are inferred from the analyses of sedimentary carbonate oxygen isotopes. Recent variations correspond with changes in the North Pacific Index, a measure of the intensity and position of the Aleutian Low, the semi-permanent low-pressure system located over the Gulf of Alaska. This suggests that the Jellybean oxygen isotope record reflects changes in Aleutian Low intensity and position since ∼7500 cal BP. Late Holocene changes correspond with changes in North Pacific salmon abundance and shifts in atmospheric circulation over the Beaufort Sea. Marcella Lake is a small, hydrologically-closed, evaporation sensitive lake. Former water levels were driven by changes in regional effective moisture and reconstructed by multi-proxy analyses of sediment cores from a shallow-to-deep water transect. Marcella Lake water oxygen isotopes are strongly affected by evaporation allowing past humidity changes to be reconstructed from sedimentary calcite oxygen isotope ratios. The record from Jellybean Lake accounts for variations related to atmospheric circulation and ambient temperature changes allowing an estimation of changes in ambient humidity driven by evaporation. Results suggest that late Holocene increases in aridity in the interior regions of the southwest Yukon are the result of long-term and sustained Aleutian Low intensifications and/or eastward shifts ∼1200 and 400 cal BP. The following climatic patterns are emerging. The early Holocene was warm and dry. Between 9000 and 10,000 cal BP there was a rapid increase in lake level suggesting a shift in the precipitation regime. The early aridity may have prevented the establishment of spruce forest. Between 7500 and 4000 cal BP, lake levels were relatively stable 5-m below modern levels and Aleutian Low intensity was predominantly weaker and/or westward than present. Between ∼4500 and 3000 cal BP the Aleutian Low intensified and/or shifted eastward before weakening and/or shifting westward further between 3000 and 2000 cal BP. (Abstract shortened by UMI.)

High-pressure granulite terranes are important sources of information for understanding deep-crustal architecture and processes related to the evolution and stabilization of continental lithosphere. However, one of the most critical challenges is to understand how, and on what timescales, large exposures of lowermost continental crust are exhumed to the Earth's surface. In the East Lake Athabasca region of the western Canadian Shield, high pressure granulites (∼1.0+ GPa) make up one of the largest exposed deep crustal terranes in the world (>20,000 km2). Important insight into the exhumation history of this region come from the study of the kinematics, timing, and metamorphic evolution of a several km-wide, oblique-slip, thrust-sense mylonitic shear zone (Legs Lake shear zone) that forms a major boundary of the high-pressure terrane. The juxtaposition of crustal levels across this structure is more than 20 km. Integrated structural and petrologic analysis of the shear zone and its wallrocks, combined with in situ electron microprobe monazite Th-U-Pb geochronology and U-Pb isotope geochronology, suggest a multi-stage exhumation history for the high-pressure region that occurred over a period of >100 million years. Similar studies of a second and younger fault zone and of the cross-cutting relationships between the two shear zone systems (with displacements of up to 110 km), provide an explanation for the present-day distribution of high pressure rocks in the region and have important implications for the early growth of this part of Laurentia.